diff --git a/core/modules/taxonomy/src/Tests/RssTest.php b/core/modules/taxonomy/tests/src/Functional/RssTest.php
similarity index 96%
rename from core/modules/taxonomy/src/Tests/RssTest.php
rename to core/modules/taxonomy/tests/src/Functional/RssTest.php
index c4f48846b4..8ab8933018 100644
--- a/core/modules/taxonomy/src/Tests/RssTest.php
+++ b/core/modules/taxonomy/tests/src/Functional/RssTest.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\taxonomy\Tests;
+namespace Drupal\Tests\taxonomy\Functional;
 
 use Drupal\Core\Field\FieldStorageDefinitionInterface;
 use Drupal\views\Views;
@@ -106,7 +106,8 @@ public function testTaxonomyRss() {
 
     // Test that the feed page exists for the term.
     $this->drupalGet("taxonomy/term/{$term1->id()}/feed");
-    $this->assertTrue(!empty($this->cssSelect('rss[version="2.0"]')), "Feed page is RSS.");
+    $assert = $this->assertSession();
+    $assert->responseHeaderContains('Content-Type', 'application/rss+xml');
 
     // Check that the "Exception value" is disabled by default.
     $this->drupalGet('taxonomy/term/all/feed');
diff --git a/core/modules/taxonomy/src/Tests/TermTest.php b/core/modules/taxonomy/tests/src/Functional/TermTest.php
similarity index 94%
rename from core/modules/taxonomy/src/Tests/TermTest.php
rename to core/modules/taxonomy/tests/src/Functional/TermTest.php
index 54309c4237..574efa073e 100644
--- a/core/modules/taxonomy/src/Tests/TermTest.php
+++ b/core/modules/taxonomy/tests/src/Functional/TermTest.php
@@ -1,12 +1,13 @@
 <?php
 
-namespace Drupal\taxonomy\Tests;
+namespace Drupal\Tests\taxonomy\Functional;
 
 use Drupal\Component\Utility\Tags;
 use Drupal\Core\Field\FieldStorageDefinitionInterface;
 use Drupal\field\Entity\FieldConfig;
 use Drupal\taxonomy\Entity\Term;
 use Drupal\taxonomy\Entity\Vocabulary;
+use Drupal\Tests\taxonomy\Functional\TaxonomyTestBase;
 
 /**
  * Tests load, save and delete for taxonomy terms.
@@ -389,6 +390,7 @@ public function testTermInterface() {
    * Save, edit and delete a term using the user interface.
    */
   public function testTermReorder() {
+    $assert = $this->assertSession();
     $this->createTerm($this->vocabulary);
     $this->createTerm($this->vocabulary);
     $this->createTerm($this->vocabulary);
@@ -406,21 +408,30 @@ public function testTermReorder() {
     // "tid:1:0[depth]", and "tid:1:0[weight]". Change the order to term2,
     // term3, term1 by setting weight property, make term3 a child of term2 by
     // setting the parent and depth properties, and update all hidden fields.
-    $edit = [
+    $hidden_edit = [
       'terms[tid:' . $term2->id() . ':0][term][tid]' => $term2->id(),
       'terms[tid:' . $term2->id() . ':0][term][parent]' => 0,
       'terms[tid:' . $term2->id() . ':0][term][depth]' => 0,
-      'terms[tid:' . $term2->id() . ':0][weight]' => 0,
       'terms[tid:' . $term3->id() . ':0][term][tid]' => $term3->id(),
       'terms[tid:' . $term3->id() . ':0][term][parent]' => $term2->id(),
       'terms[tid:' . $term3->id() . ':0][term][depth]' => 1,
-      'terms[tid:' . $term3->id() . ':0][weight]' => 1,
       'terms[tid:' . $term1->id() . ':0][term][tid]' => $term1->id(),
       'terms[tid:' . $term1->id() . ':0][term][parent]' => 0,
       'terms[tid:' . $term1->id() . ':0][term][depth]' => 0,
+    ];
+    // Because we can't post hidden form elements, we have to change them in
+    // code here, and then submit.
+    foreach ($hidden_edit as $field => $value) {
+      $node = $assert->hiddenFieldExists($field);
+      $node->setValue($value);
+    }
+    // Edit non-hidden elements within drupalPostForm().
+    $edit = [
+      'terms[tid:' . $term2->id() . ':0][weight]' => 0,
+      'terms[tid:' . $term3->id() . ':0][weight]' => 1,
       'terms[tid:' . $term1->id() . ':0][weight]' => 2,
     ];
-    $this->drupalPostForm(NULL, $edit, t('Save'));
+    $this->drupalPostForm(NULL, $edit, 'Save');
 
     $taxonomy_storage->resetCache();
     $terms = $taxonomy_storage->loadTree($this->vocabulary->id());
@@ -570,7 +581,7 @@ public function testTermBreadcrumbs() {
     ];
 
     // Create the term.
-    $this->drupalPostForm('admin/structure/taxonomy/manage/' . $this->vocabulary->id() . '/add', $edit, t('Save'));
+    $this->drupalPostForm('admin/structure/taxonomy/manage/' . $this->vocabulary->id() . '/add', $edit, 'Save');
 
     $terms = taxonomy_term_load_multiple_by_name($edit['name[0][value]']);
     $term = reset($terms);
@@ -578,19 +589,19 @@ public function testTermBreadcrumbs() {
 
     // Check the breadcrumb on the term edit page.
     $this->drupalGet('taxonomy/term/' . $term->id() . '/edit');
-    $breadcrumbs = $this->cssSelect('nav.breadcrumb ol li a');
+    $breadcrumbs = $this->getSession()->getPage()->findAll('css', 'nav.breadcrumb ol li a');
     $this->assertIdentical(count($breadcrumbs), 2, 'The breadcrumbs are present on the page.');
-    $this->assertIdentical((string) $breadcrumbs[0], 'Home', 'First breadcrumb text is Home');
-    $this->assertIdentical((string) $breadcrumbs[1], $term->label(), 'Second breadcrumb text is term name on term edit page.');
-    $this->assertEscaped((string) $breadcrumbs[1], 'breadcrumbs displayed and escaped.');
+    $this->assertIdentical($breadcrumbs[0]->getText(), 'Home', 'First breadcrumb text is Home');
+    $this->assertIdentical($breadcrumbs[1]->getText(), $term->label(), 'Second breadcrumb text is term name on term edit page.');
+    $this->assertEscaped($breadcrumbs[1]->getText(), 'breadcrumbs displayed and escaped.');
 
     // Check the breadcrumb on the term delete page.
     $this->drupalGet('taxonomy/term/' . $term->id() . '/delete');
-    $breadcrumbs = $this->cssSelect('nav.breadcrumb ol li a');
+    $breadcrumbs = $this->getSession()->getPage()->findAll('css', 'nav.breadcrumb ol li a');
     $this->assertIdentical(count($breadcrumbs), 2, 'The breadcrumbs are present on the page.');
-    $this->assertIdentical((string) $breadcrumbs[0], 'Home', 'First breadcrumb text is Home');
-    $this->assertIdentical((string) $breadcrumbs[1], $term->label(), 'Second breadcrumb text is term name on term delete page.');
-    $this->assertEscaped((string) $breadcrumbs[1], 'breadcrumbs displayed and escaped.');
+    $this->assertIdentical($breadcrumbs[0]->getText(), 'Home', 'First breadcrumb text is Home');
+    $this->assertIdentical($breadcrumbs[1]->getText(), $term->label(), 'Second breadcrumb text is term name on term delete page.');
+    $this->assertEscaped($breadcrumbs[1]->getText(), 'breadcrumbs displayed and escaped.');
   }
 
 }
diff --git a/core/modules/taxonomy/src/Tests/TermTranslationTest.php b/core/modules/taxonomy/tests/src/Functional/TermTranslationTest.php
similarity index 97%
rename from core/modules/taxonomy/src/Tests/TermTranslationTest.php
rename to core/modules/taxonomy/tests/src/Functional/TermTranslationTest.php
index ccb16f611d..bd9085017b 100644
--- a/core/modules/taxonomy/src/Tests/TermTranslationTest.php
+++ b/core/modules/taxonomy/tests/src/Functional/TermTranslationTest.php
@@ -1,9 +1,9 @@
 <?php
 
-namespace Drupal\taxonomy\Tests;
+namespace Drupal\Tests\taxonomy\Functional;
 
 use Drupal\Core\Url;
-use Drupal\system\Tests\Menu\AssertBreadcrumbTrait;
+use Drupal\Tests\system\Functional\Menu\AssertBreadcrumbTrait;
 
 /**
  * Tests for proper breadcrumb translation.